Electric lamp and discharge devices – With luminescent solid or liquid material – Solid-state type
Reexamination Certificate
1998-03-27
2001-03-06
Patel, Ashok (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Solid-state type
C313S506000, C313S112000, C359S585000
Reexamination Certificate
active
06198215
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an anti-light-reflective film which is applied to display apparatuses using an EL (electroluminescent) device or liquid crystal device and to photomasks, to a method for manufacturing the film, and to an EL device having an anti-light-reflective function.
2. Description of the Related Art
As an EL device which is used as a display apparatus for office automation or factory automation equipment, there is known an EL device having a three-layer structure as illustrated in FIG.
7
. In
FIG. 7
, transparent strip electrodes
12
made of ITO (indium tin oxide) are patterned on a transparent substrate
10
made of glass so as to be spaced uniformly in parallel to each other. On the strip electrodes
12
, a first insulating layer
13
made of an film of oxide such as Al
2
O
3
, SiO
2
, TiO
2
, or of nitride such as Si
3
N
4
, a luminescent layer
14
having a composition in which a very little amount of Mn or the like is added as a luminescence center to a host material of ZnS, ZnSe, SrS or the like and a second insulating layer
15
of a similar oxide or nitride film to the first insulating film
13
are laminated in this order, and then back strip electrodes
16
made of Al are patterned in a direction perpendicular to the transparent strip electrodes
12
so as to be spaced uniformly in parallel to each other.
In the thus structured EL device is realized a dot matrix display as desired, by selectively applying a voltage to the transparent electrodes
12
and the back electrodes
16
, and then causing portions of the luminescent layer
14
which are at intersections of the transparent electrodes and the back electrodes to emit light in the form of dot in an arbitrary combination.
It is well known in the art that, in front of the aluminum back electrodes
16
, i.e. on the side of the second insulating layer
15
, an anti-light-reflective film having a laminated structure of a Cr oxide film or a Cr metal film and a laminated structure of a Mo oxide film or a Mo metal film is disposed so as to reduce the reflection of ambient light and improve the contrast ratio of display. For the purpose of absorbing the reflected light, Japanese Unexamined Patent Publication JP-A 61-211997 (1986) discloses utilization of a laminated structure of island-structure type absorbing film/transparent dielectric film/island-structure type absorbing film/metallic thin film by using an island-structure type absorbing film made of Mo, Ta, Cr, Si or the like for a back electrode film.
In the prior art structure in which the back electrodes are made of aluminum as described above, however, since the reflected light from the aluminum back electrodes is rather strong in an bright environment such as the outdoors in the daytime, the contrast ratio (on/off ratio) of display is decreased with the result that the display quality is impaired. In order to solve the problem, JP-A 61-211997 is directed to improvement of the structure of a device so that ambient light (incident light) is absorbed in the device and the intensity of reflected light to the ambient light is controlled to 10% or below.
Although in JP-A 61-211997 is used a Cr metal film for the island-structure absorbing film, the Cr metal film can be replaced with a Cr oxide film. Since in the case of an anti-light-reflective film made of a Cr oxide film or a Cr metal film, toxic dichromatic ion is generated in waste water in an etching process in patterning electrodes, disposal of the waste water in the course of processing cannot be easily conducted. Moreover, since a laminated film including an island-structure type film made of Mo, Ta, Cr, Si or the like requires two or more layers of absorbing film, the laminated film is structured by four or more layers composed of island-structure type absorbing film/transparent dielectric film/island-structure type absorbing film/metal thin film with the result that it takes time to form a laminated film and the cost increases.
An anti-light-reflective film using a Mo oxide film or a Mo metal film in place of a Cr oxide film or a Cr metal film overcomes the above problems occurring by use of a Cr oxide film or a Cr metal film, with regard to the performance, the structure, and the disposal of waste water in a producing process. However, the Mo oxide film and Mo metal film has low water resistance in the manufacturing process, and hence it is difficult to conduct an aqueous-system patterning process. According to experiments by the present inventor, a metallic film is peeled off because the Mo oxide film and Mo metal film is dissolved in a cleaning process by water.
In this way, the prior arts in which a Cr oxide film, a Cr metal film, a Mo oxide film and a Mo metal film are used have drawbacks. In the process of manufacturing a display device, especially an EL device, a structure satisfying all requirements of: being free from a problem of waste water treatment; adaptability to environment; low production cost; and stability in the manufacturing process; has not been realized.
SUMMARY OF THE INVENTION
It is hence an object of the invention to realize an anti-light-reflective film in which the above drawbacks are overcome, additionally to provide a novel structure of an anti-light-reflective film in which high contrast is realized, and to provide a method for producing the film and an EL device using the film.
The anti-light-reflective film of the invention is featured by a two-layer structure composed of (Mo:X)ON and a metal film. The EL device of the invention is featured by utilizing the anti-light-reflective film. In particular, the method for manufacturing the EL device is featured by controlling the refractive index and thickness of (Mo:X)ON film.
In a first aspect of the invention, an anti-light-reflective film comprises:
a molybdenum oxynitride ((Mo:X)ON(X=Si,W,Ta or Ni)) film including any one of Si, W, Ta and Ni, and
one or more metal films selected from among Ni, Al and Mo films,
the films forming a laminated structure.
According to the first aspect of the invention, an anti-light-reflective film of two layer structure type is realized which has high water resistance, and is free of a problem of waste water treatment in a patterning process.
In a second aspect of the invention, the anti-light-reflective film of the first aspect of the invention is characterized in that the molybdenum oxynitride film is selected to have a refractive index in a range of 2.2 to 2.8 and to have a thickness in a range of 30 nm to 60 nm; and
the metal film is selected to have a thickness in a range of 300 nm to 600 nm.
In a third aspect of the invention, the anti-light-reflective film of the second aspect of the invention is characterized in that the molybdenum oxynitride film is selected to have a refractive index in a range of 2.4 to 2.6 and to have a thickness of 40 nm to 50 nm.
In a fourth aspect of the invention, the anti-light-reflective film of the third aspect of the invention is characterized in that the molybdenum oxynitride film is selected to have a refractive index of 2.4 and to have a thickness of 50 nm.
According to the second aspect of the invention, the intensity of reflected light can be sufficiently suppressed. According to the third aspect of the invention, the intensity of reflected light can be more sufficiently suppressed. According to the fourth aspect of the invention, the intensity of reflected light can be most sufficiently suppressed.
In a fifth aspect of the invention, a method for producing an anti-light-reflective film comprising a molybdenum oxynitride ((Mo:X)ON(X=Si,W,Ta or Ni)) film including any one of Si, W, Ta and Ni, and any one or more metal films of Ni, Al and Mo films, the films forming a laminated structure,
the method comprising a step of forming the molybdenum oxynitride film by sputtering in which a flow rate of oxygen is set in a range of 2 ccm to 4 ccm.
According to the fifth aspect of the invention, determining the flow rate of oxygen in sputtering as described above enables to form
Niboshi Manabu
Shimoyama Hiroyuki
Nixon & Vanderhye PC
Patel Ashok
Sharp Kabushiki Kaisha
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